This invention relates to composite prelaminated tapes for forming closures for disposable diapers which can be opened and refastened without destroying either the diaper or the tape.
At least as early as 1955, it had been suggested to use strips of normally tacky and pressure-sensitive adhesive tape to secure conventional cloth diapers on an infant; see, e.g., Chambers U.S. Pat. No. 2,714,889 and Ekberg U.S. Pat. No. 3,221,738. A few years later, when disposable diapers became extremely popular, strips of pressure-sensitive adhesive tape were again employed as closures; see, e.g., Gellert U.S. Pat. No. 3,620,217.
A disposable diaper typically has a thin, flexible, low density polyethylene film cover, an absorbent filler inside of the cover, and a porous inner liner overlying the filler. The diaper is positioned at the crotch of an infant with the two ends of the diaper extending toward the front and back respectively. Edges on each side of the diaper are then either positioned adjacent to each other or overlapped with a strip of pressure-sensitive adhesive tape being adhered to the cover at the border adjacent each of the two edges and holding the diaper closed.
After a tape closure has been opened, it is frequently discovered that the diaper has not been soiled and hence that there is no need to replace it. If the diaper cover has not been torn, a second strip of tape can sometimes be applied as a replacement closure, but this is often inconvenient. As a result, considerable work has been undertaken to develop a tape diaper closure that is not only capable of bonding firmly to the diaper cover but is also capable of being opened without destroying the tape diaper closure or the diaper cover and subsequently reclosed. Closures of this type have generally involved a combination of two or more tapes, one of which remains permanently adhered to one edge of the diaper and the other being removably adhered to the other edge of the diaper. Examples of such products are shown in Ness et al, U.S. Pat. No. 3,951,149; Milnamow U.S. Pat. No. 3,987,793; Feldman et al, U.S. Pat. No. 3,999,546; Richman et al, U.S. Pat. No. 4,020,842; and Schotz, U.S. Pat. No. 4,227,530.
Typically, tape closures for diapers are fabricated by positionably mounting a plurality of individual rolls of the appropriate tapes and combining them in situ to form a composite strip of tape, the width of which is substantially the same as the length of the diaper closure to be fabricated. The composite roll is then severed at right angles to the edges of the composite strip at intervals corresponding to the width of the desired tape closure and adhered at an appropriate location along the border adjacent the sides of the diaper as exemplified in Hamaguchi et al U.S. Pat. No. 3,616,114. Although this manufacturing process is effective, relatively sophisticated machinery is necessary to accomplish the superimposition of several rolls of tape to form a composite strip of tape in situ. Thus, it is desirable to provide diaper manufacturers with a composite prelaminated tape in a single roll from which closures may readily be prepared.
Commonly assigned copending U.S. patent application Ser. No. 891,131 of Pape et al describes a composite prelaminated tape comprising a pressure-sensitive adhesive fastening tape subdivided into bonded and fastening sections comprising a release tape, a fingerlift and a unifying strip. A problem which may be experienced with the Pape et al composite tape is the exposure of a small area of adhesive adjacent to the unifying strip which tends to adhere to the outer diaper cover and tear the cover upon opening of the closure. The present invention is an improvement over that invention.